Richard J. Bell

Rebuilding fish communities: the ghost of fisheries past and the virtue of patience

The ecosystem approach to management requires the status of individual species to be considered in a community context. We conducted a comparative ecosystem analysis of the Georges Bank and North Sea fish communities to determine the extent to which biological diversity is restored when fishing pressure is reduced. First, fishing mortality estimates were combined to quantify the community-level intensity and selectivity of fishing pressure. Second, standardized bottom-trawl survey data were used to investigate the temporal trends in community metrics. Third, a size-based, multispecies model (LeMans) was simulated to test the response of community metrics to both hypothetical and observed changes in fishing pressure in the two communities. These temperate North Atlantic fish communities have much in common, including a history of overfishing. In recent decades fishing pressure has been reduced, and some species have started to rebuild. The Georges Bank fishery has been more selective, and fishing pressure was reduced sooner. The two communities have similar levels of size diversity and biomass per unit area, but fundamentally different community structure. The North Sea is dominated by smaller species and has lower evenness than Georges Bank. These fundamental differences in community structure are not explained by recent fishing patterns. The multispecies model was able to predict the observed changes in community metrics better on Georges Bank, where rebuilding is more apparent than in the North Sea. Model simulations predicted hysteresis in rebuilding community metrics toward their unfished levels, particularly in the North Sea. Species in the community rebuild at different rates, with smaller prey species outpacing their large predators and overshooting their pre-exploitation abundances. This indirect effect of predator release delays the rebuilding of community structure and biodiversity. Therefore community rebuilding is not just the sum of single-species rebuilding plans. Management strategies that account for interspecific interactions will be needed to restore biodiversity and community structure.

Inventory of Intertidal Marine Habitats, Boston Harbor Islands National Park Area

Abstract The intertidal zone of the 34 islands that are the Boston Harbor Islands national park area encompasses over half of the total park area, thereby representing a significant natural resource. The purpose of this study was to inventory the intertidal zone by classifying and mapping all habitats and compiling species lists for major taxonomic groups. The Boston Harbor Intertidal Classification System was developed for mapping substrate and biotic assemblage types—a system specific to the local area, but capable of application throughout the Gulf of Maine. Intertidal habitats were mapped from GPS-based field delineations. Mixed coarse, consisting of rocks, boulders, cobbles, gravel, shell, and sand, was by far the most common substrate type; however, the islands were variable with a total of 13 discrete substrate types mapped, ranging from bedrock and boulders to mud. The outer islands (e.g., Outer and Little Brewster) were dominated by rocky substrate, while islands close to the mainland (e.g., Thompson, Slate) had high percentages of fine sediments. Of the 31 biotic assemblages mapped, Mytilus edulis (blue mussel) reef was the dominant assemblage on many of the middle and Hingham Bay islands, while the outer islands had assemblages common to the more exposed rocky substrates. The species inventory recorded 95 species of invertebrates, 70 marine algae, and 15 vascular plants. The information generated from this inventory will provide a foundation for natural resource management decisions, design of a long-term intertidal monitoring program, and identification of research needs.

Changes in the size structure of marine fish communities

Changes in the size structure of marine fish communities Richard J. Bell*, Jeremy S. Collie, Trevor A. Branch, Michael J. Fogarty, Coilin Minto, and Daniel Ricard Northeast Fisheries Science Center, National Marine Fisheries Service, Narragansett, RI, USA Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA Northeast Fisheries Science Center, National Marine Fisheries Service, Woods Hole, MA, USA Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Hydrobiology, Ceske Budejovice, Czech Republic *Corresponding author: tel: þ401 874 6511; fax: þ401 874 6145; e-mail: rich.bell@tnc.org. Present address: The Nature Conservancy, Narragansett, RI, USA. Present address: Fisheries and Oceans Canada, Gulf Fisheries Centre, Moncton, NB, Canada.

Discard Estimates from Self-Reported Catch Data: an Example from the U.S. Northeast Shelf

AbstractDiscarded catch can account for a significant amount of fishing mortality and can be a major source of uncertainty when calculating total removals for stock assessments and management. Observers provide estimates on the types and quantity of fish that are caught, but observer coverage of a fleet can often vary directly with funding. On the Northeast U.S. shelf, the Northeast Fisheries Observer Program (NEFOP) has collected data on catch and discards for assessment and management purposes since 1989. The Cooperative Research Study Fleet (hereafter “Study Fleet”), working with the Northeast Fisheries Science Center, collects self-reported catch and discards from commercial vessels; however, the Study Fleet program was not developed as an observer program, and these data are not used for management. The number of vessels reporting data in the Study Fleet program is much smaller than the total number of vessels recorded through the observer program (NEFOP plus the At-Sea Monitoring Program), and unlik...